To be illegal under Title VII, sexual harassment must be found to have been based on the harassee’s gender. Harassment based on other factors–for example, simply personal dislike–is not unlawful sexual harassment, however reprehensible it might be.
In 1998, the Supreme Court reaffirmed that sexual harassment is illegal under Title VII not because it includes offensive, sexually explicit remarks, but because it is directed at a harassee due to his or her gender. This is in the Oncale case found in your textbook. It is important to note that in the Oncale case, while the Supreme Court determined that sexual harassment that violates Title VII may be perpetrated by a non-homosexual person of the same gender as the harassee, it did not hold that plaintiff Oncale himself had necessarily been a sexual harassment victim. The Court simply found that the appeals court had improperly dismissed the case based solely on the argument that there could be no sexual harassment when the harasser and the harassee were of the same gender.